2D Bi2Te3/Si heterostructure with high thermoelectric power factor enabled by interface regulated carrier injection

Abstract

It has been highly demanded to optimize the charge carrier concentration in 2D Bi2Te3 to achieve enhanced thermoelectric performance. This work reveals that, constructing 2D Bi2Te3/Si heterostructure with tuned interfacial electronic band structure can meet the above needs. When the work function in Si substrate is decreased from 4.6 to 4.06 eV, the charge carrier concentration and electron effective mass are increased simultaneously. Consequently, the electrical conductivity of 2D Bi2Te3 on n++-Si has reaches up to 1250 S·cm−1, which is 90% higher than the counterpart on SiO2/Si substrate, although the Seebeck coefficient in these two samples is around −103 μV·K−1. The resultant power factor of 2D Bi2Te3/n++-Si heterostructure is 13.4 μW·cm−1·K−2, which is one of the best values among similar studies ever reported. This work demonstrates a facile way to improve thermoelectric properties via interfacial engineering in a heterostructure.